The motor will swap in with no problems, the trans though, you'lll need to get an aftermarket crossmemeber kit to properly mount the trans. The '96 Corvette block still has the front block engine mount points like the early small blocks.

Honestly though, I'd recommend going with a good 383 for your Impala that makes a lot of torque, on the trans side, for any latemodel trans (stick or automatic) you'll need to get a crossmember kit form someone like Late Great Chevy.